Abstarct: The Ariz–Chahgaz area, covering about 400 km², is a part of the northern Bafq region within the Central Iran structural zone. The major lithological units of this area can be divided into four to five groups: 1-Late Neoproterozoic baxsement Complex This unit is predominantly mextamorphic (regional mextamorphic rocks), comprising a diverse assemblage of mextapelites, mextapsammites, mextacarbonates, mextabasalts, and deformed granitoids (mylonitized). Index mextamorphic minerals such as garnet, staurolite, andalusite, kyanite, and possibly calcium-rich grossular garnet occur within the mextamorphic baxsement complexes from Bafq to Posht-e-Badam area. The unit is strongly folded and deformed, with scattered outcrops in both the northern and southern parts of the Ariz–Chahgaz area. 2-Igneous, Volcano-Sedimentary (Rizu and Dezu series), and Sedimentary Rocks This assemblage includes a wide spectrum of intrusive and extrusive igneous rocks, bimodal mafic–felsic volcanics, pyroclastics, and volcano-sedimentary rocks. These rocks form the focal point of this dissertation. In some areas, they have been affected by hydrothermal fluids, undergoing extensive mextasomatism accompanied by mineralization of Fe, Th, and U. A part of the mineralization is also related to magmatic differentiation or incomplete mixing of Fe-rich fluids. The main intrusive bodies in the area include: Chahgaz Diorite, Zarigan Granite. These two intrusions display markedly different characteristics. Chahgaz diorites contain mafic minerals, opaque Fe-rich phases, and titanomagnetite, whereas Zarigan granites are nearly free of ferromagnesian or mafic minerals. Geochemical studies indicate that Chahgaz diorites originated from fractional crystallization of mantle-derived basic magmas, while Zarigan granites crystallized from melts generated by partial melting of lower continental crust with granulitic composition. The felsic magmas experienced significant mineralogical and geochemical evolution during ascent and emplacement. The Zarigan granitoid pluton shows notable textural variation (from coarse-grained to fine-grained, porphyroidic and porphyritic macro and microstrucures) from SE to NW, suggesting progressively shallower levels of emplacement toward the NW. Graphic, micrographic, perthitic, and anti-perthitic textures are common, indicating crystallization near the minimum of granitic systerms during fractional crystallization (0.5–2 kbar, 650–750 °C). Numerous diabaxse dikes cut the Zarigan granitoid and its host rocks. Their geochemical composition ranges from gabbro to diorite and monzonite, but petrographic evidence (abundant green hornblende, absence of pyroxene and olivine, and microstructural features) favors classification as diorite to microdiorite, or more generally as diabaxse dikes. Their magmas have a close affinity with those of the Chahgaz diorite, belonging to the same magmatic system but emplaced at slightly different times, possibly from common magma reservoirs. Geochemical signatures (REE patterns normalized to chondrite, spider diagrams, and other parameters, together with comparisons to adjacent terranes (NE Bafq, South of Bahabad, North of the Zarand, etc.), suggest that these magmas originated during the Late Neoproterozoic–Early Cambrian from an enriched subcontinental mantle source similar to OIB (or subcontinental lithospheric mantle). These events occurred within an extensional tectonic regime (intra-continental rifting) along the northern margin of Gondwana. Magmatism ceased by the end of the Early Cambrian, and reffered tp relatively stable tectonic conditions in lower Paeozoic Iran. This is corrolated by the Lalun Formation, a thick sandstone succession with fluvial–deltaic facies, reaching up to 1500 m in thickness in areas such as Soutj of Ravar–North of Zarand. The Lalun Formation is widely exposed in Iran. Renewed mafic magmatism began in the Late Cambrian and continued into the Carboniferous, expressed as basaltic lavas, diabaxse dikes, and small mafic intrusions. These processes ultimately contributed to the formation of the Paleo-Tethys, which lies beyond the scope of this study. Thermobarometry of dioritic to granodioritic rocks of the Ariz area (baxsement-related) indicates crystallization at pressures of 1.3–2.8 kbar and temperatures of 713–861 °C. Thermobarometry of the Chahgaz granitoid or Chah Gaz diorite or gabbrodiorite (rift-related), baxsed on total Al in amphibole (hornblende), suggests crystallization at 600–750 °C and pressures of 0.25–1.25 kbar. Ten representative rock samples were selected for zircon separation and U–Pb dating. Due to insufficient zircon yield, three samples could not be dated. Seven samples were successfully dated using the U–Pb method. Five new ages from diorite, granodiorite, and alkali-feldspar granite of the Ariz area indicate magmatic crystallization and emplacement near the Precambrian –Lower Paleozoic boundary (551 ± 11 to 520 ± 12 Ma). This research is baxsed on extensive fieldwork (more than 40 days and over 150 stations), which constitutes a major strength compared to previous studies. Results highlight the overlooked interplay between compressional Late Neoproterozoic complexes and extensional Late Neoproterozoic–Early Paleozoic complexes, often expressed as fault-bounded bodies. Misinterpretation of these relations has led to erroneous tectonic models. While most felsic rocks plot in the VAG field of geochemical diagrams and have been interpreted as volcanic arc granites, geochemical evidence from mafic rocks and mineralization data supports their affiliation with an extensional setting. No major Cu deposits are reported in the northern Bafq rift system, but iron ore bodies exceeding one billion tons, enriched in LREE, HFSE, LILE, and Pb, are present. Extensive alkaline mextasomatism has produced diverse mineral assemblages including apatite, actinolite, tremolite, talc, epidote, chlorite, calcite, and augite–diopside.